A number of approaches have been taken in the construction and design of all-terrain vehicles for military, commercial or recreational use. Typically, however, these vehicles utilize the basic construction of a military tank in which tracks located on either side of the vehicle body can be driven in unison or separately controlled in speed to effect steering of the vehicle both in a forward and reverse direction. In the past, the track-type vehicles have suffered definite limitations insofar as their use over rough terrain is concerned, since they tend to lose traction in passing over ditches, craters, ridges and other obstacles. Moreover, the unbalancing effect in passing over sharp ridges or other obstacles is such as to cause loss of control and possible damage to the vehicle or injury to the operator. Similarly, these vehicles have difficulty in negotiating soft or muddy terrain.
In the past, it has been proposed to equip vehicles of the type described with roller assemblies or auxiliary propulsion elements at opposite ends. For example, U.S. Pat. No. 3,477,535 to H. M. Wyatt discloses a vehicle having front and rear roller assemblies which can be lowered to raise the vehicle off the ground but has limited traction or propulsion capabilities insofar as being able to advance the vehicle over rough terrain is concerned. U.S. Pat. No. 2,489,349 to C. C. White is directed to a track-type vehicle equipped with disks mounted on articulated frames at opposite ends of the vehicle. The vehicle can be propelled only by the disk assemblies; however, owing to the construction of the disks, their utilization as a means of propulsion is largely limited to hard, smooth ground and not to rough or soggy terrain. U.S. Pat. No. 3,570,604 to P. L. Allard similarly is directed to a vehicle provided with spiked wheels journaled on hingedly mounted frames at the front and rear ends of the vehicle. The frames can be lowered until the wheels engage the ground and the vehicle body is elevated whereupon an independent hydraulic motor must be activated to rotate the wheels and advance the vehicle, its principal intended use being as a lawn conditioning element. Other representative approaches and designs relating to articulated roller assemblies mounted at opposite ends of a vehicle are disclosed in U.S. Pat. Nos. 1,358,575 to E. Rimailho; 2,012,090 to N. Straussler; 2,959,201 to R. G. Le Tourneau; 3,054,467 to E. W. Seiler; 3,057,319 to E. A. Wagner; 3,417,832 to J. J. Ziccardi; 3,698,499 to R. V. Albertson; 3,794,121 to D. A. Drozak; 3,820,497 to N. G. Konijn; and 4,157,877 to B. R. Lee.
Thus to my knowledge no one has devised an all-terrain vehicle provided with articulated tractive roller assemblies mounted at opposite ends of the vehicle which is capable of negotiating rough or muddy terrain while possessing both digging and ground clearing capabilities.